Firstly, you ALWAYS want to buy resale. It should be a red week at high season for the resort you are purchasing for the best trading power. Secondly, you want to purchase this week at a resort with the least expensive maintenance fees (with the best record for low yearly increases). Don't bother with one bedroom units as two bedrooms are not that much more and trade much better/easily. Here's what I did for one of my weeks. I purchase all of my resales from a company called holiday group in Washington state. They are very reputable and efficient and have great prices. You can easily see what's available on their website, I check it frequently. Orlando is very easy to trade into, so I would not purchase in Orlando, maintenance fees tend to be high, in my opinion. I purchased a prime ski week, two bedroom unit at Fairmont Vacation Villas in British Columbia, Canada just for trading (it is a five star, Interval International). I purchased this unit for 1,200 and my maintenance fees are around $440 per year. That enables me to trade into ANY five star property in Orlando that has availability.
As far as properties, I am an owner at Orange Lake (RCI gold crown 2 br) and love that resort. I think it is by far the best "self-contained" resort in Orlando, in that there is such a vast amount of activities to choose from, you don't have to leave the resort for fun, if you don't want to. We traded a week we had banked for a THREE bedroom to use the end of Sept/beg October.
As far as Interval properties, I love the Marriott Grande Vista and Westgate lakes. The Grande Vista has elgant and extremely comfortable rooms, IMO any Marriott resort should be wonderful. Westgate Lakes is another favorite. I have been there three times, twice in an efficiency and once in a two bedroom. The units are clean and very comfortable, has a wonderful spa, nice pools, and a lake. Both the Grande Vista and Westgate Lakes are very convient to all of the attractions in Orlando. Feel free to contact me if you have any other questions about purchase a resale or these resorts. Good luck.